This invention relates to a lift for moving a wheelchair over a stairway.
The instant wheelchair lift was developed as a result of the development by the assignee of the instant invention of an aircraft passenger loading bridge which enables people to pass from the ground level of an airport to the door of an aircraft through a completely enclosed passageway. The ground level loading bridge is described in detail in U.S. Pat. No. 4,161,049 which is assigned to the assignee of the instant invention. Such a passenger loading bridge incorporates a stairway since, without the use of the stairway, the angle of the walkway from the entrance of the bridge to the exit at the doorway of the aircraft would be unacceptably steep. Use of a stairway presents a problem for transporting people in wheelchairs through the bridge. One common method of transporting a wheelchair over a stairway is to simply have people carry the wheelchair up and down the stairway. However, lifting a wheelchair over a stairway is slow, difficult and requires at least two people to handle the wheelchair. Consequently, the instant invention was developed to provide a device for quickly and easily transporting a person in a wheelchair over a stairway in a passenger loading bridge.
A number of wheelchair lift systems are presently available. However, most of these systems are not adaptable for use in the stairway of a passenger loading bridge for a variety of reasons. In some of the systems, the tracks or rails for guiding a chair supporting carriage or platform over the stairway project into the stairway when the system is not in use. In other systems the platform supporting a wheelchair cannot be detached from the carriage which moves it. Therefore, although the platform can be folded when not in use, it still projects a significant distance into the stairway and impedes the flow of passenger traffic over the stairway. An additional problem with most of the lift systems presently available is that they have a portion of their operating mechanism exposed when the lift is not in operation. A device having an exposed operating mechanism is not suitable for use in a public conveyance such as a passenger loading bridge.
In a lift used for moving a wheelchair over a stairway in a passenger loading bridge, it is desirable to be able to store the lift when it is not in use in such a manner that it does not project over the stairway and impede the movement of passengers using the stairway. Further, it is desirable to have a wheelchair lift in which the platform carrying the wheelchair can be removed from the carriage supporting the platform so that it can be stored out of the way of passenger traffic when not in use.
It is also desirable to have a wheelchair lift in which the operating mechanism is inaccessible when the lift is not in operation.